As a recording technique utilizing solid state properties of chalcogenide material, a phase change memory and a phase-change optical disk are given. As phase change material used for the phase change memory and the phase-change optical disk, chalcogenide material containing Te (tellurium) is known.
U.S. Pat. No. 5,254,382 (Patent Document 1) discloses an optical disk medium using chalcogenide material expressed by {(GeyTe1-y)a (SbzTe1-z)1-a}1-b (In1-xTex)b (here, 0.4≦y ≦0.6, 0.3≦x≦0.6, 0.4≦z≦0.6, 0.1≦a≦0.5, 0.01≦b≦0.3) as a recording layer. The chalcogenide material is obtained by adding In to Ge—Sb—Te in order to enhance stability of an amorphous state to improve long-term data storage property while maintaining such characteristic that crystallization can be obtained at a high speed.
On the other hand, U.S. Pat. No. 5,883,827 (Patent Document 2) describes a non-volatile memory using a chalcogenide material film in detail. The non-volatile memory is a phase change memory where the atomic arrangement of a phase change material film changes according to Joule heat generated by current flowing in the phase change material film itself and a cooling rate so that storage information is written. For example, operating current tends to increase in order to apply a temperature exceeding 600° C. obtained by Joule heat to a phase change material layer to once melt the phase change material film upon amorphizing the phase change material layer, where a resistance value of the phase change material film changes in a range from two digits to three digits according to a state of the phase change material film.
In the electric phase change memory, research has been advanced centering around one using Ge2Sb2Te5, for example, Japanese Patent Application Laid-Open Publication No. 2002-109797 (Patent Document 3) discloses a recording element using GeSbTe. In addition, Japanese Patent Application Laid-Open Publication No. 2003-100991 (Patent Document 4) discloses a technique regarding a memory using chalcogenide material. Further, it has been reported that rewrite can be performed 1012 times in a phase change memory using a phase-change film made of Ge2Sb2Te5 (see Non-Patent Document 1). Moreover, a technique regarding a phase change memory using a crystal-growth-dominant material has been reported (see Non-Patent Document 2).
Patent Document 1: U.S. Pat. No. 5,254,382
Patent Document 2: U.S. Pat. No. 5,883,827
Patent Document 3: Japanese Patent Application Laid-Open Publication No. 2002-109797
Patent Document 4: Japanese Patent Application Laid-Open Publication No. 2003-100991
Non-Patent Document 1: “IEEE International Electron Devices meeting, TECHNICAL DIGEST”, (USA), 2001, p. 803-806
Non-Patent Document 2: “Nature Materials”, (USA), 2005, Vol. 4, p. 347-351